Portion of an insole



FIG. 1 is a perspective view of a portion of an insole showing our new design;

FIG. 2 is a bottom view thereof;

FIG. 3 is a side view thereof;

FIG. 4 is an opposite side view thereof;

FIG. 5 is a front view thereof; and,

FIG. 6 is a rear view thereof.

The broken lines in the drawings illustrate portions of a portion of an insole that form no part of the claimed design. 

CLAIM The ornamental design for a portion of an insole, as shown and described. 